Diodes Incorporated ZTX553STZ

Overview

ZTX553STZ from Zetex Semiconductors (now Diodes Incorporated) is a PNP silicon planar medium-power bipolar junction transistor rated for −100 V V_CEO, −120 V V_CBO, and −1 A continuous collector current, with 1 W power dissipation at 25°C ambient. It operates across −55°C to +200°C junction temperature range and is used in linear regulation, high-voltage switching, and industrial relay drivers where robust PNP gain and breakdown margin are required.

For engineers reviewing the ZTX553STZ datasheet, ZTX553STZ pinout, ZTX553STZ application, or ZTX553STZ equivalent, key selection criteria include verified V_CEO(sus) = −100 V, h_FE = 40–200 at I_C = −150 mA / −1 A, f_T = 150 MHz, V_CE(sat) = −0.25 V @ I_C = −150 mA / I_B = −15 mA, and TO-92 compatible E-Line package mechanical fit.

Technical Context

The ZTX553STZ is a medium-power PNP BJT optimized for stable DC amplification and fast-switching operation in high-voltage analog and digital circuits. Its design supports sustained collector-emitter voltage up to −100 V under pulsed conditions and delivers consistent h_FE across two decades of collector current (−10 mA to −1 A), with guaranteed minimum gain of 40 at I_C = −1 A.

It features low saturation voltages (V_CE(sat) ≤ −0.25 V, V_BE(sat) ≤ −1.1 V) under forced β = 10 drive, enabling efficient active-mode control in discrete power stages. Transition frequency remains stable at 150 MHz under −50 mA / −10 V bias, supporting sub-100 ns switching transitions in pulse applications.

Key Specifications

Pinout & Package

Supplied in an E-Line TO-92 compatible plastic package with standard lead configuration: Emitter (E), Base (B), Collector (C) arranged left-to-right when viewing the flat side with leads downward.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP medium-power transistor applications.

Compared with MJD2955G and BC807-40, the ZTX553STZ uniquely balances −100 V breakdown, −1 A current, and TO-92 compatibility-making it optimal for legacy through-hole designs requiring high-voltage PNP switching without heatsinking.

Availability

ZTX553STZ is available at Aetrix Electronics and suitable for industrial relay drivers, linear voltage regulators, high-voltage signal inversion, and discrete PWM motor control stages requiring stable component supply and long-term obsolescence resilience.

Supply support for ZTX553STZ includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Zetex Semiconductors, now part of Diodes Incorporated, specialized in high-performance discrete semiconductors for analog, power, and interface applications before its 2008 acquisition.

The ZTX series was developed for ruggedized medium-power linear and switching applications demanding wide temperature operation, high breakdown voltage, and consistent gain-particularly in industrial control and power conversion.

FAQ

Is ZTX553STZ RoHS compliant?

Yes, ZTX553STZ is RoHS compliant and halogen-free per Diodes Incorporated's product change notice PCN-2017-015. The TO-92 package uses matte tin-plated leads and meets JEDEC J-STD-020 reflow profiles for lead-free assembly.

What is the maximum safe operating temperature for continuous operation?

The ZTX553STZ has a maximum junction temperature of +200°C and storage range of −55°C to +200°C. For continuous operation at −1 A, ambient must be held ≤ 75°C assuming no heatsink and natural convection, based on θ_JA ≈ 175°C/W and P_tot = 1 W derating.

Can ZTX553STZ replace ZTX552 in existing designs?

Yes, ZTX553STZ is a direct upgrade to ZTX552 with identical pinout and package but improved ratings: V_CBO increased from −100 V to −120 V and V_CEO from −80 V to −100 V. All electrical characteristics are equal or superior; no layout or drive changes are needed.

Does ZTX553STZ require a base resistor in switching applications?

Yes-a base resistor is mandatory to limit I_B and ensure proper saturation. For I_C = −150 mA with β = 10, I_B ≈ −15 mA requires R_B ≈ 330 Ω when driven from −5 V logic (accounting for V_BE(sat) ≈ −1.1 V). Undriven base risks thermal runaway due to leakage multiplication.